Tone-balancing element

ABSTRACT

A laminated piano soundboard includes a treble and bass bridge for transmitting vibrations from the piano strings and a plurality of spaced-apart ribs for localizing the vibrations at the center, prime resonating area of the soundboard. Since the laminated character of the soundboard tends to inhibit localization thereby adversely effecting its tonal quality, a tone-balancing element is provided for assuring enhanced resonance.

United States Patent Andersen [541 TONE-BALANCING ELEMENT [72] inventor:Clifford W. Andersen, De Kalb, ill.

[73] Assignee: The Wurlitzer Company, Chicago, Ill. 22 Filed: June 1,1970 [21] Appl. No.: 41,978

[52] US. Cl ..84/192 {51] Int. ..Gl0c 3/06 [581 Field oiSearch..84/192,194,189,l93, 184, 84/187 [56} References Cited UNITED STATESPATENTS 777,939 12/1904 Clemons ..84/ 192 1,747,307 2/1930 Leland et...84/192 2,469,522 5/1949 Sauerland ..84/ 192 Feb. 15, 1972 3,248,9905/1966 Bolin ..84/1 89 3,444,771 5/1969 Taguchi ....84/ l 94 3,459,0918/1969 Taguchi ..84/ l 92 Primary Examiner-Richard B. WilkinsonAssistant Examiner-John F. Gonzales Attorney-Olson, Trexler, Wolters &Bushnell [57] ABSTRACT A laminated piano soundboard includes a trebleand bass bridge for transmitting vibrations from the piano strings and nplurality of spaced-apart ribs for localizing the vibrations at thecenter, prime resonating area of the soundboard. Since the laminatedcharacter of the soundboard tends to inhibit localization therebyadversely efiecting its tonal quality, a tonebalancing element isprovided for assuring enhanced resonance.

6 Claims, 7 Drawing Figures PATENTEUFEB 15 I972 sum 2 OF 2 iiiii/""'"" WTONE-BALANCING ELEMENT SUMMARY OF THE INVENTION DISTINCTION OVER THEPRIOR ART AND OBJECTS A piano soundboard is a resonator to which thevibrations of piano strings are transmitted for producing tonalqualities.

In the past, such soundboards were made out of solid boards which wereselectively tapered and provided with transversely extending rib membersfor localizing the vibrations in a manner which would most enhance thetonal qualities. More recently, some pianos have utilized laminatedrather than solid soundboards. However, it has been found to beimpossible to satisfactorily taper a laminated board. Therefore, in thepast, such laminated soundboards were characterized by poor tonalqualities.

Accordingly, a general object of the present invention is to provide anew and improved laminated soundboard which is characterized by greatertonal qualities than those of the prior art.

Another object of the present invention is to provide a laminatedsoundboard which vibrates in a controlled fashion.

A more particular object of the present invention is to provide a noveltone-balancing element to be used with a laminated soundboard forcontrolling the standing sound waves thereof.

Yet a more particular object of the present invention is to provide atone-balancing element which attenuates the standing sound waves of asoundboard and localizes them in the center of the soundboard.

These and other objects and features of the invention will become moreapparent from a reading of the following descriptions.

The above objects are achieved and the disadvantages of the prior artare eliminated by providing a piano soundboard comprising a laminatedresonating board which is preferably made from three-ply mahogany andwhich is coupled to the strings of a piano through a treble bridge and abass bridge. A plurality of ribs and a unique tone-balancing element areselectively mounted on opposite sides of the resonating board forattenuating the standing sound waves of the board and localizing them ina manner most effective for producing the highest tonal quality.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a front elevational view of a soundboard constructed accordingto the invention;

FIG. 2 is a front elevational view of the soundboard of FIG.

.1 coupled to the piano strings of an upright piano;

DETAILED DESCRIPTION Referring now in detail to the drawings,specifically to FIG. I, a piano soundboard constructed in accordancewith the present invention is indicated generally by the referencenumeral 10. The soundboard comprises a substantially rectangularlaminated resonator board 12 which is preferably fashioned from threeplys of mahogany wood and which is coupled, through a treble bridge 14and bass bridge 16, to the vibrating strings of a piano for transmittinga series of vibrations to the board 12 and thereby producing standingsound waves. A plurality of longitudinal rib members 18, positioned onselective areas of the back side of the resonator board, providerigidity to those areas so that the remaining surface thereof may freelyvibrate for most advantageously localizing the standing sound waves. Thebridges and rib members are preferably mounted to the resonator board bya resinous plastic waterproof glue so that the board is not impregnatedwith moisture. Such moisture has been found to reduce the tonal qualityof a soundboard.

The surface of resonator board 12 is selectively tapered in the samemanner as the prior art solid boards, but due to their laminatedcharacteristic, the various tapered sections do not exhibit apredictable quality of sound which is otherwise found in solid resonatorboards. In this regard, it has been found that a plurality ofconventional rib members alone, do not properly localize the standingsound waves. Accordingly, a carefully sized and shaped tone-balancingelement 20, selectively glued to the front or string-connecting side ofthe resonator board attenuates the standing sound waves and localizesthem at the center where they have been found to produce the best tonalquality.

Turning to FIG. 2, an upright piano 22 utilizing the soundboard 10includes a vertically mounted substantially rectangular housing or frame24 supporting the soundboard so that the treble and bass bridges extendout beyond the frame for engagement with the vibrating portions of aplurality of treble strings 26 and bass strings 28 respectively.

The treble strings, which are connected to the top of frame 24 by aplurality of string pins 30, extend down and slightly to the left, asviewed in FIG. 2, so as to pass over and engage the treble bridge 14 andthereafter terminate at a bridge 32 which is mounted to the bottom andone side of the frame and which extends across the soundboard slightlybelow the treble bridge. A plurality of string pins 31 secure thestrings to the bridge 32. The bass strings 28, which are connected tothe top of frame 24 by string pins 34, extend downward, slightly to theright and over the treble strings for engagement with the bass bridge 16and are thereafter secured to the bottom of the frame by a group ofstring pins 36.

Vibrations are conventionally imparted to the strings by an actionmechanism (not shown) which is actuated by a corresponding key of thepiano keyboard. These vibrations, which include differing harmonicfrequencies depending upon the length, diameter, tension and density ofthe strings, are transmitted to the resonator board through the bridgesand develop a standing sound wave. Both the rib members 18 and thetone-balancing element 20 provide attenuation and localization, so thatthe sound waves produce an enhanced tone.

Referring now to FIGS. 3 and 5, the rib members 18 are equally laterallyspaced on the back of resonator board 12 and are aligned substantiallyperpendicularly to a line which bisects the upper leftand lowerright-hand corners of the board, as viewed in FIG. 3. The rib membersare of varying length so as to extend substantially from one edge of theboard to the other, the members being relieved on common ends to formbeveled shoulders 38 which are sized in accordance with their respectivepositions on the resonating board to constrain or localize thetransmitted vibrations in areas designated by the reference numeral 40which lie therebetween. Each of the members tapers downward, at a slightangle, from the uppermost point of its shoulder so that a beveledshoulder may be eliminated at the other end.

As stated above, rib members 18, when constructed in the aforementionedmanner, do not alone localize the vibrations in the desired fashion.Absent the tone-balancing element 20, there would be a tendency for mostof the vibration to develop at the upper right-hand corner of the boardas viewed in FIG. 3

It should be noted that three of the four vertices of frame 24 includeintegrally connected triangular extensions or supports 42 which convertthe effective resonating area from a rectangular to a hexagonal area.This, in turn, further directs the vibrations to the center.

Returning to FIG. 1, the tone-balancing element 20 comprises a flat,preferably laminated wafer, as seen in FIG. 4, in the form of aright-angle triangle having a hypotenuse 43 joining remaining sides orlegs 44 and 46 which meet at the rightangle, the side 46 being ofslightly greater length than that of side 44. The tone-balancing elementis positioned on the resonator board so that its right-angled vertex ispositioned adjacent the upper left-hand vertex of the resonator board,as viewed in FIG. 1, so that the hypotenuse 43 extends perpendicular tothe rib members 18. This arrangement prevents the transmitted vibrationsfrom localizing adjacent the corner of the soundboard and attenuates thestanding sound waves for redirecting them toward the center of theresonator board, thus achieving the highest quality of piano tone.

Turning to FIGS. 6 and 7, there is shown a modified tonebalancingelement 50 which also takes the form of a rightangle triangle having ahypotenuse side 52 joining two perpendicular sides 54 and 56 and whichis positioned in the same location as that of tone-balancing element 20.However, the hypotenuse side thereof includes a plurality of equallylaterally spaced semicylindrical scallops 58 which further calize thestanding sound waves developed in the resonator board. Specifically, asseen in FIG. 6, the scallops are positioned, alternatively, over andbetween underlying rib members 18 so that, as the vibrations of theresonator board tend to develop, the scallops tend to attenuate them andredirect them towards the center thereof.

While particular embodiments of the invention have been shown, it shouldbe understood, of course, that the invention is not limited theretosince many modifications may be made. It is, therefore, contemplated tocover by the present application any such modifications as fall withinthe true spirit and scope of the appended claims.

The invention is claimed as follows:

1. A piano soundboard assembly comprising: a resonator board forproducing standing sound waves; a plurality of ribs mounted to one sideof said board in substantially parallel arrangement; and a planar,triangular tone-balancing element mounted to the opposite side of saidboard, said tone-balancing element being disposed in a corner region ofsaid board with the longest edge generally at a right angle to thelongitudinal axes of said ribs, whereby to locate standing sound wavesgenerally centrally of said board.

2. A piano soundboard assembly according to claim I wherein saidresonator board is substantially rectangular in shape for defining asubstantially similarly shaped resonating surface area and wherein saidtone-balancing element forms a right triangle having a hypotenuse sideand first and second sides extending from the right-angled vertexthereof, said first and second sides being positioned parallel tointersecting joined edges of said resonator board.

3. A piano soundboard assembly according to claim 2 wherein saidresonator board includes triangular support means mounted to three ofits four vertices, said support means converting the substantiallyrectangular resonating surface area of said resonator board to asubstantially hexagonal resonating surface area.

4. A piano soundboard assembly according to claim 2 wherein thehypotenuse side of said tone-balancing elements includes a plurality ofscallops which further localize said standing sound waves.

5. A piano soundboard assembly according to claim 4 wherein saidscallops are equally laterally spaced along the hypotenuse of saidtone-balancing element, alternatively over and between said rib members.

6. A piano soundboard assembly according to claim 1 wherein saidresonator board comprises a plurality of wood plies.

1. A piano soundboard assembly comprising: a resonator board forproducing standing sound waves; a plurality of ribs mounted to one sideof said board in substantially parallel arrangement; and a planar,triangular tone-balancing element mounted to the opposite side of saidboard, said tone-balancing element being disposed in a corner region ofsaid board with the longest edge generally at a right angle to thelongitudinal axes of said ribs, whereby to locate standing sound wavesgenerally centrally of said board.
 2. A piano soundboard assemblyaccording to claim 1 wherein said resonator board is substantiallyrectangular in shape for defining a substantially similarly shapedresonating surface area and wherein said tone-balancing element forms aright triangle having a hypotenuse side and first and second sidesextending from the right-angled vertex thereof, said first and secondsides being positioned parallel to intersecting joined edges of saidresonator board.
 3. A piano soundboard assembly according to claim 2wherein said resonator board includes triangular support means mountedto three of its four vertices, said support means converting thesubstantially rectangular resonaTing surface area of said resonatorboard to a substantially hexagonal resonating surface area.
 4. A pianosoundboard assembly according to claim 2 wherein the hypotenuse side ofsaid tone-balancing elements includes a plurality of scallops whichfurther localize said standing sound waves.
 5. A piano soundboardassembly according to claim 4 wherein said scallops are equallylaterally spaced along the hypotenuse of said tone-balancing element,alternatively over and between said rib members.
 6. A piano soundboardassembly according to claim 1 wherein said resonator board comprises aplurality of wood plies.